org.apache.juneau.internal.MultiIterable Maven / Gradle / Ivy
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package org.apache.juneau.internal;
import static org.apache.juneau.internal.ThrowableUtils.*;
import java.util.*;
/**
* Utility class for defining an iterator over one or more iterables.
*
* @param The element class type.
*/
public class MultiIterable implements Iterable {
final List> iterators = new LinkedList<>();
/**
* Constructor.
*
* @param iterators The list of iterators to iterate over.
*/
@SuppressWarnings("unchecked")
public MultiIterable(Iterator...iterators) {
for (Iterator i : iterators)
append(i);
}
/**
* Appends the specified iterator to this list of iterators.
*
* @param iterator The iterator to append.
* @return This object (for method chaining).
*/
public MultiIterable append(Iterator iterator) {
assertFieldNotNull(iterator, "iterator");
this.iterators.add(iterator);
return this;
}
@Override /* Iterable */
public Iterator iterator() {
return new Iterator() {
Iterator> i1 = iterators.iterator();
Iterator i2 = i1.hasNext() ? i1.next() : null;
@Override /* Iterator */
public boolean hasNext() {
while (i2 != null && ! i2.hasNext())
i2 = (i1.hasNext() ? i1.next() : null);
return (i2 != null);
}
@Override /* Iterator */
public E next() {
hasNext();
if (i2 == null)
throw new NoSuchElementException();
return i2.next();
}
@Override /* Iterator */
public void remove() {
if (i2 == null)
throw new NoSuchElementException();
i2.remove();
}
};
}
}